Effect of different mouthwashes on the shear bond strength and surface roughness of intraoral and heat‑cured soft liners

The present study aimed to determine the effect of mouthwashes on the shear bond strength (SBS) and surface roughness (SR) of soft liners.

In this in vitro study, a total of 72 samples were prepared to evaluate the SBS (n = 36 for each liner). An autopolymerized (Mollosil Plus) and a heat‑polymerized liner(Molloplast B) were injected in between two blocks of heat‑processed acrylic resin (Triplex). The samples in each liner group were subdivided into three subgroups. Control group samples were totally stored in distilled water. In test groups, samples were immersed in chlorhexidine (CHX) or mouthwash containing ginger extract for 30 min daily. After 20 days, the SBSs were evaluated using a universal testing machine. To evaluate the SR, 30 disk-shaped samples (15mm*10mm) were prepared for each type of liners and stored in the similar solutions; distilled water, CHX and ginger mouthwash (n=10). SR was measured at 1 day and after 90 days with a profilometer. One‑way ANOVA, independent t‑test, and paired t‑test were used to analyze data. P < 0.05 was considered statistically significant.

The SBS in Molloplast B liner was significantly higher than Mollosil regardless of type of solution (P < 0.001).In both liners, the mean SBS was not statistically different between the three groups of solutions. Changes in SR were not statistically significant after 90 days, except for the Mollosil group, immersed in ginger extract solution which was increased (P = 0.04).

SBS of either group of liners did not change in both mouthwashes; However, SBS of heat‑polymerized liner was higher than autopolymerized in all groups. Ginger extract‑containing mouthwash increased SR of autopolymerized liner used in this study; whereas, there were no significant changes in the heat‑cured liner. According to this study, CHX can be used for the disinfection of prosthesis lined with either type of liners.